New heterogeneous catalysts containing platinum group metals recovered from a spent catalytic converter

Abstract

A spent catalytic converter was treated with concentrated HCl and hydrogen peroxide in very mild conditions to extract approximately half of its platinum group metals (PGMs) content, mainly as chlorides. The noble metals were subsequently charged into functionalized mesoporous silica by complexation with mercapto groups. A combination of methods was employed to prove the transfer of PGMs and to characterize the materials (inductively coupled plasma optical emission spectrometry [ICP‐OES], Fourier transform‐infrared [FT‐IR] spectroscopy, electrospray ionization mass spectrometry [ESI‐MS], thermogravimetric analysis [TGA], X‐ray photoelectron spectroscopy [XPS], X‐ray diffraction, and UV–Vis spectrophotometry). The resulted PGM‐loaded silica was successfully tested as a new heterogeneous catalyst for hydrosilylation and oxidation reactions. Information about the nature of the PGMs species extracted and loaded completes the existing literature data. The scrap cordierite may be valorized for retention of pollutants from water and also catalyzes the hydrosilylation reaction based on the remaining PGMs. Flexible composite materials can be obtained by incorporating scrap cordierite as filler and crosslinking catalyst into a silicone matrix, significantly enhancing the dielectric permittivity. Thus, complete re‐valorization of the main components of the catalytic converter as high‐added‐value materials was achieved at laboratory level, with very low energy demanding procedures.

Functionalized Mesoporous Silica as Doxorubicin Carriers and Cytotoxicity Boosters

“…Five silica materials were prepared, adapting a procedure from the literature [ 30 ], followed by chemical modification ( Scheme 1 ), that is, a silica with ca. 10% mercaptopropyl groups, (Sil2), a mesoporous silica derived from this one (MSil2), two silica carrying glucoside-modified functional groups, derived from Sil2 and MSil2, coded Sil3 and MSil3, respectively, and a mesoporous silica with ca.…”

“…Two mesoporous silica materials: MSil1 and MSil2, with methyl and 3-mercaptopropyl organic groups, respectively, attached to silicon, were obtained, following in general terms a previously reported procedure [ 30 ], that is, co-hydrolysis of alkoxysilanes using CTAB surfactant as template, in alkaline medium, followed by template elimination in acidic conditions.…”

Platinum Group Metals: Green Recovery from Spent Auto-Catalysts and Reuse in New Catalysts—A Review

“…In another work by Racles et al [178] a SAC was treated with HCl+H 2 O 2 in very mild conditions to extract approximately half of its PGMs content, mainly as chlorides. The noble metals were subsequently charged into functionalized mesoporous silica by complexation with mercapto groups to synthetize a heterogeneous catalyst for hydrosilylation and oxidation reactions.…”

Molecular and silica-supported metal complexes as new catalysts for hydrosilylation

“…25 The formation of Pt(0) colloids /particles is generally associated with catalyst deactivation, 12 but the involvement of small Pt nanoparticles in certain hydrosilylation reactions has also been reported. 26 In previous studies, [29][30][31] several metal complexes, obtained in our laboratory with original siloxanebased ligands or functionalized silica have been presented, and their potential applications as catalysts for different types of reactions have been preliminary tested. These are Pt(IV) or Fe(III) molecular complexes based on pyridyl or isocyanide disiloxane ligands, and Pt or Pt/Pd complexes of pyridil-or thiol-modified silica, respectively.…”